Thank you all for the responses, especially Pete's mammoth opus, which I have printed copy of. Some sound advice there.

I think most of the sorts Green Wellies described have moved on (in one way or another...). Five years ago the local allotments were nearly empty and the council was seriously considering closing them and using the land to extend the cemetery next door (did I tell you these allotments are particularly rich in nutrients?...). The remnants of the old allotment society made one last almighty push, and five years later all the plots are being cultivated, the turnover is very slow, there's a waiting list and the council have just given over an adjacent strip of land (not on the cemetery side!) to create additional plots. As well as fruit and veg, there are quite a few chicken runs and the Co-op and the council are helping the allotment society set up an apiary. Apparently, most of the plots are organically cultivated or heading that way. Seems like a great time to join. The place is a monument to make-do-and-mend: there's a kind of mad inventor chaos prevailing - some very neat plots but lots of salvaged bits-and-pieces and what you could only describe as junkyard art with practical applications. The previous occupants have left us some well weathered railway sleepers (raised beds here we come) and a compost bin and a lot of weeds...

I'm looking forward to planting a few fruit bushes. Other than that, my neighbour and I are having our first planning meeting this week. I keep you posted.